1. Field of the Invention
The present invention relates generally to condensation polymers such as polyesters and polyamides, and more specifically to nylon 66. The present invention utilizes a trifunctional monomer to impart functionality to condensation polymers such as polyester or nylon, such as stain resistance, flame resistance, antistatic behavior, soil resistance, surface lubrication, or thermal or ultraviolet stabilization.
2. Description of Related Art
Triaminononane (TAN), also known as aminomethyl-1,8-diaminooctane, is an agent employed to provide chain branching in polyamide polymers used in fibers for such materials as clothing and carpets. Such chain branching has been used to provide processing benefits such as dying, crimping and friction false twisting, as well as to add strength to fibers. For example, in U.S. Pat. No. 4,596,742, TAN was employed to provide branch chains in a sheathed nylon 66. The sheaths contain the branching agent which has functional groups reactive with nylon 66 while the core does not contain branch chains. Such structure is reported to improve elongation and crimp development. Similar improvement to partially oriented nylon is more fully reported by J. H. Southern et al in Textile Res. Journal, 62(8), pp. 437-444 (1992), as well as in U.S. Pat. No. 4,721,650. Partially oriented nylon yarn is reported in this publication as being more highly responsive to high speed texturing and friction false twisting. These advantages are said to be obtained by either increasing the molecular weight of the polymer or by providing branch chains in the polymer by adding trifunctional compounds.
While branched polyamides have been known in the art, the benefits of branch chains have been limited. Outside of processing applications, improvements to polyamide fibers have been made through the use of additives. These additives usually coat the fibers after they are formed, or are combined with the polymer as a melt additive. However, coating may be lost with wear of the fiber. Diffusion of additives from the polymer also causes blooming, affecting the surface appearance of the product. Polymers used for medical or food applications cannot contain leachable additives for health, safety, and/or regulatory reasons. Additionally, large amounts of melt additives cannot be used: they are costly, require additional processing steps, create spinning difficulties, and reduce the strength of the fiber. As with the coat, materials added to the polymer in such a manner are not permanent.
Previous methods to overcome such problems have been to incorporate the desired functional group into the backbone of the polymer. In U.S. Pat. No. 4,092,302, phosphorous compounds were included as an integral part of the polymer chains to give fibers anti-static and flame-resistant properties. Tetraalkyl phosphonium salts were incorporated into the polymer chain in GB 1,442,581 as well.
There has been discovered a novel method to impart improved properties to condensation polyesters and polyamides, particularly nylon 66, wherein trifunctional monomers are incorporated into the polymer chain, having reactive sites available to which functional molecules may be permanently bonded.